Many types of container closures are well known. One example is a hinged lid or flap which must be manually opened and closed, and usually manually held out of the way to keep the container open while it is being tilted. Another example is a ring pull as on a conventional drinks can which must be manually opened and cannot then be re-closed.
In many applications, the need for manual opening and closing is undesirable or inconvenient. For containers with a ring pull-type closure it may be disadvantageous that the container cannot be re-closed when some of the contents remain inside, since they may spill accidentally or become contaminated.